This invention relates to fluid flow controllers for pneumatically contoured supports and more particularly to low energy consumption fluid flow control systems for use in controlling fluid flow in a pneumatically operated system having expandable fluid chambers with a contoured support surface and wherein the fluid control systems include a microvalve having a condition responsive actuator for controlling a relatively large volume of flow through a valve unit.
U.S. patent application Ser. No. 08/808,511, filed Feb. 27, 1997, discloses a pneumatically controlled seating system in which an electronic control module selectively controls energization of a valve unit for controlling air flow from a pressure source to a plurality of pressurizable expandable fluid chambers or air cells.
The valve unit is a low energy consumption valve that is opened and closed by a valve actuator having a low consumption of power during operation of the system. One suitable valve for use in such systems is shown in U.S. Pat. No. 5,447,286 wherein a piezo actuated vent valve is provided to control the air flow through the valve unit. The piezo actuation is provided by a cantilevered member that has a layer of ceramic material bonded to a carrier plate. The ceramic material deforms when a voltage is imposed thereon by the control module. Deformation of the ceramic layer will deflect the carrier plate to open and close the valve.
Additionally, microvalves formed within silicon wafers are known as set-forth in U.S. Pat. Nos. 4,826,131; 4,895,500; 5,909,078 and 5,994,816. Such valves are characterized by low energy consumption and small size and by including a component that is responsive to an imposed condition to move in a manner that will control a valving element to open and close for controlling fluid flow, e.g., to a pressurizable expandable chamber.
One problem with systems for pneumatically contouring support surfaces such as vehicle seats, furniture seats and pneumatically controlled beds is how to interconnect valve control units with pressurized expandable chambers and with a pressure source in a compact and an efficient manner.
The problem of providing a compactly arranged and easily assembled fluid flow controller for pneumatically contoured supports and such a controller having low energy consumption is addressed in the present invention by incorporating a microvalve formed on a silicon wafer and selectively combined with a controller to provide multiple flow paths to expandable fluid chambers or air cells of a seating or body support system and including at least one microvalve controlled exhaust path from one or more expandable chambers or air cells.
One feature of the present invention is to provide a fluid flow controller of the aforesaid type in which a microvalve arrangement has a printed circuit board supporting a common manifold and one or more microvalves for supplying one or more expandable chambers or air cells.
A further feature is to provide such a fluid flow controller including a microvalve on the printed circuit board that is dedicated solely to providing an exhaust path from the common manifold when predetermined one or more of the expandable chambers or air cells are connected by one or more of the supply microvalves to the common manifold.
Yet another feature is to provide the common manifold as a single tube connected to a lock fitting on the microvalve.
Yet another feature is to provide a single tube connected to a pressure source.
Another feature of the present invention is to provide a fluid flow controller of the aforesaid type in which a first microvalve array includes a supply microvalve directly connected without the use of tubing to one of the expandable chambers or air cells and to a common manifold.
Still another feature is to commonly connect the microvalve to a pressure source and a common circuit board forming an assembly with a suitable controller for electrically connecting each of the microvalves and the pressure source for selectively or commonly pressurizing each of the expandable chambers or air cells during a pump up mode of operation.
Yet another feature is to provide such a microvalve array having an exhaust mode of operation from one or all of the expandable chambers or air cells provided by a microvalve exhaust valve that is connected to the common manifold and operated to exhaust one or more of the expandable chambers or air cells when the power supply to the pressure source is cut-off and one or more of the microvalves is opened in accordance with signals from the controller.
A further feature is to provide such an arrangement wherein a second array of supply microvalves are connected to a second plurality of expandable chambers or air cells and to a second common manifold having a source of pressure connected thereto and a second exhaust microvalve connected thereto and wherein the operation of the second array of supply microvalves, pump and exhaust microvalve is in accordance with a desired operating program that can be the same or different from that of the first microvalves.
Still another feature of the present invention is to provide such an arrangement having microvalve and pressurizable expandable chamber or air cell connections wherein the microvalve is connected to be carried as part of the expandable chamber or air cell either externally or internally of the expandable chamber or air cell.
A still further feature of the present invention is to provide such an arrangement having a common single tube manifold for supply of pressurized fluid through a supply microvalve to one or more expandable chambers or cells and to provide an individual exhaust microvalve at each expandable chamber or cell or group of expandable chambers or cells defining a zone of more than one expandable chambers or cells.
Yet another feature of the present invention is to provide such an arrangement having a multi-functional microvalve module wherein all the supply microvalves are mounted on a common silicon wafer including a single inlet; a condition responsive region in the wafer to control flow to an outlet for supplying one or more expandable chambers or air cells and or to exhaust path from the one or more expandable chambers or air cells.
A further feature is to provide microvalve elements in such controllers wherein an actuator is provided that is condition responsive and operative to control a valve element to control fluid flow with respect to manifolds, expandable chambers and exhausts.
A still further feature is to provide the microvalve elements of the preceding object with a beam that is temperature responsive.